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Full text of "Alaskan glacier studies of the National Geographic Society in the Yakutat Bay, Prince William Sound and lower Copper River regions"

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in the position of the glacial front. In 1899 a considerable embayment existed in the eastern third of this glacier, but was not present in 1905 and 1909."
Advance. It is clear that there was more or less continuous retreat of Harriman Glacier during the decade following its discovery; but between 1909 and 1910, an advance was instituted. This was clearly shown on August 1, 1910, when a comparison with the glacier front of the Harriman Expedition photograph; alluded to by Grant, showed an advance of the western margin of 700 feet (PL CXXXVII), accompanied by great thickening at the terminus. The western gravel bar, shown in another Harriman Expedition photograph, upon which the margin of the glacier terminated in 1899, was not visible at the time of our only visit, which was near high tide while the 1899 picture was taken when the tide was part way out. On the land near by, however, we saw the glacier advancing and destroying alder by overriding and by sliding down of ice blocks.
The 1909 observations of Grant and Higgins make it certain that the change from retreat to advance came between 1909 and 1910 and that the whole of the 700 feet advance was during the last year. The eastern margin also advanced, coming forward the whole distance that it had retreated from 1899 to 1909. In 1910 it seemed to be slightly beyond the 1899 position and there was much thickening of the eastern terminus, which Gilbert says was "low and irregular" and rested on a "detrital bank" in 1899, which was not visible in 1910. There seems to have been far more iceberg discharge in 1910 than in 1899.
In addition to the advance and thickening of the part of the eastern margin on the shores of the bay, the glacier was advancing on the land. Annual plants in the barren zone were being buried and a ridge of push moraine a foot or two high lay at the base of a lofty, uncrevassed ice cliff. On August 1, this ice cliff was 158 feet from an older terminal moraine which marked the maximum of a former advance, doubtless before 1899.
The oscillations of Harriman Glacier during the period of observation may be summarized as follows.
Date	Oscillation	Amount	Observer
Before June 27, 1899 June 27, 1899, to Aug. 20, 1905 Aug. 20, 1905, to June 29, 1909 June 29, 1909, to Aug. 1, 1910	Probably retreat Retreat Retreat continued Advance	About 350 feet 700 feet 700-1050 feet	Gilbert Grant and Paige Grant and Higgins Martin
Dirty Glacier. There are a number of smaller ice tongues in southern Harriman Fiord, including one or two in hanging valleys above Harriman Glacier (PL CXXXVII), of which they are disconnected tributaries, and eight or more farther north in the fiord which were formerly tributaries of the extended Harriman Glacier.
Of these ice tongues the Dirty Glacier, on the eastern side of the fiord, just north of Harriman Glacier terminus, is exceptional in having ablation moraine cover over a large proportion of the terminus. Its n6v fields coalesce with those of Harriman Glacier, and although it has a steeper grade than the Harriman it contrasts strongly with neighboring